Beam training of a radio transceiver device

ABSTRACT

A method is performed for beam training of a radio transceiver device comprising at least two antenna arrays. During the beam training, a first set of occurrences of a reference signal is received using all the antenna arrays and such that one respective occurrence of the reference signal is received in one single wide beam at each of all the antenna arrays. During the beam training, a second set of occurrences of the reference signal using less than all antenna arrays and such that one respective occurrence of the reference signal is received in each respective narrow at each of the less than all antenna arrays. Which of the less than all antenna arrays to receive the second set of occurrences of the reference signal is determined based on evaluation of reception of the first set of occurrences of the reference signal at each of all the antenna arrays.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/739,383 filed on Dec. 22, 2017, which is a 35 U.S.C. § 371national stage application of PCT International Application No.PCT/EP2017/080604 filed on Nov. 28, 2017, the disclosures and contentsof which are incorporated herein by reference in their entireties.

TECHNICAL FIELD

Embodiments presented herein relate to a method, a radio transceiverdevice, a computer program, and a computer program product for beamtraining of the radio transceiver device. Embodiments presented hereinfurther relate to a method, another radio transceiver device, a computerprogram, and a computer program product for beam training of the radiotransceiver device.

BACKGROUND

In communications networks, there may be a challenge to obtain goodperformance and capacity for a given communications protocol, itsparameters and the physical environment in which the communicationsnetwork is deployed.

For example, for future generations of mobile communications networks,frequency bands at many different carrier frequencies could be needed.For example, low such frequency bands could be needed to achievesufficient network coverage for terminal devices and higher frequencybands (e.g. at millimeter wavelengths (mmW), i.e. near and above 30 GHz)could be needed to reach required network capacity. In general terms, athigh frequencies the propagation properties of the radio channel aremore challenging and beamforming both at the network node of the networkand at the terminal devices might be required to reach a sufficient linkbudget.

In a communications network where a transmission and reception point(TRP) at the network side uses narrow beams for transmission, at leastone of the narrow transmission beams is assumed to be discovered andmonitored for each served terminal device at the user side. This processof discovering and monitoring is referred to as beam management.

In order to perform beam management the network node uses measurements(such as received reference signal power), as obtained and reported bythe served terminal devices, on downlink reference signals such aschannel state information reference signals (CSI-RS). The beam pair forwhich the highest received reference signal power was obtained is thenused as the active beam pair link. In general terms, a beam pair isdefined by a transmission beam at the transmitting end (such as at theTRP) and a corresponding reception beam at the receiving end (such as atthe terminal device), where the transmission beam and the reception beamare selected from sets of available candidate beams so as to maximize aquality criterion (such as highest received reference signal power) fortransmission from the transmitting end to the receiving end.

In order for a terminal device to find a suitable transmission beam thenetwork node could transmit CSI-RS in different transmission beams onwhich the terminal device performs measurements and reports back the N≥1best transmission beams (where the value of N can be configured by thenetwork node).

Furthermore, the CSI-RS transmission in a given transmission beam can berepeated to allow the terminal device to evaluate suitable receptionbeam as used by the terminal device. This is sometime referred to as a“P3 procedure” or UE RX beam training.

Further, the CSI-RS can be transmitted periodically, semi-persistentlyor aperiodically (such as when being event triggered) and they can beeither shared between multiple terminal devices (users) or beuser-specific.

For terminal devices the incoming signals (such as the CSI-RS) mightarrive from all different directions, depending on the location andorientation of the terminal device relative the transmitting TRP. Henceit might be beneficial to have an antenna implementation at the terminaldevice which has the possibility to generate omni-directional-likecoverage in addition to the high gain narrow beams. One way to increasethe omni-directional coverage at an terminal is to provide the terminaldevice with multiple antenna arrays, or panels, where the antenna arrayshave mutually different pointing directions. In some aspects, a maximumtwo baseband chains at the terminal device might be used for mmWfrequencies. A larger number of baseband chains might generate too muchheat for the terminal device, especially for such large bandwidths thatare expected at these high frequencies. In some aspects the terminaldevice might therefore include just one single baseband chain, where oneand the same baseband chain can be alternatingly operatively connected,via a switch, to a respective antenna array.

During, for example, a UE RX beam training procedure, there could bemany different UE RX beams for the terminal device to evaluate. Thiswill increase overhead signalling. For example, assume that the terminalcomprises two antenna arrays and that each antenna arrays is capable ofgenerating 8 beams, then there will be in total 16 different UE RX beamsto evaluate during a UE RX beam training procedure. If one orthogonalfrequency-division multiplexing (OFDM) symbol is used for each beam,this means that in order to sweep through all beams, 16 OFDM symbols areneeded, which requires several slots of overhead signaling.

The same issue is apparent in TRP RX beam a training procedure.

Hence, there is still a need for improved beam training procedure forterminal devices as well as network nodes.

SUMMARY

An object of embodiments herein is to provide efficient beam trainingthat is applicable for radio transceiver devices such as terminaldevices and network nodes.

According to a first aspect there is presented a method for beamtraining of a radio transceiver device. The method is performed by theradio transceiver device. The radio transceiver device comprises atleast two antenna arrays. The method comprises receiving, during thebeam training, a first set of occurrences of a reference signal usingall the antenna arrays and such that one respective occurrence of thereference signal is received in one single wide beam at each of all theantenna arrays. The method comprises receiving, during the beamtraining, a second set of occurrences of the reference signal using lessthan all antenna arrays and such that one respective occurrence of thereference signal is received in each respective narrow at each of theless than all antenna arrays. Which of the less than all antenna arraysto receive the second set of occurrences of the reference signal isdetermined based on evaluation of reception of the first set ofoccurrences of the reference signal at each of all the antenna arrays.

According to a second aspect there is presented a radio transceiverdevice for beam training of the radio transceiver device. The radiotransceiver device comprises at least two antenna arrays and processingcircuitry. The processing circuitry is configured to cause the radiotransceiver device to receive, during the beam training, a first set ofoccurrences of a reference signal using all the antenna arrays and suchthat one respective occurrence of the reference signal is received inone single wide beam at each of all the antenna arrays. The processingcircuitry is configured to cause the radio transceiver device toreceive, during the beam training, a second set of occurrences of thereference signal using less than all antenna arrays and such that onerespective occurrence of the reference signal is received in eachrespective narrow beam at each of the less than all antenna arrays.Which of the less than all antenna arrays to receive the second set ofoccurrences of the reference signal is determined based on evaluation ofreception of the first set of occurrences of the reference signal ateach of all the antenna arrays.

According to a third aspect there is presented a radio transceiverdevice for beam training of the radio transceiver device. The radiotransceiver device comprises at least two antenna arrays. The radiotransceiver device comprises a receive module configured to receive,during the beam training, a first set of occurrences of a referencesignal using all the antenna arrays and such that one respectiveoccurrence of the reference signal is received in one single wide beamat each of all the antenna arrays. The radio transceiver devicecomprises a receive module configured to receive, during the beamtraining, a second set of occurrences of the reference signal using lessthan all antenna arrays and such that one respective occurrence of thereference signal is received in each respective narrow beam at each ofthe less than all antenna arrays. Which of the less than all antennaarrays to receive the second set of occurrences of the reference signalis determined based on evaluation of reception of the first set ofoccurrences of the reference signal at each of all the antenna arrays.

According to a fourth aspect there is presented a computer program forbeam training of the radio transceiver device. The computer programcomprises computer program code which, when run on processing circuitryof a radio transceiver device comprising at least two antenna arrays,causes the radio transceiver device to perform a method according to thefirst aspect.

According to a fifth aspect there is presented a method for beamtraining of another radio transceiver device. The method is performed bya radio transceiver device. The method comprises transmitting, duringthe beam training, a first set of occurrences of a reference signalaccording to antenna array configuration information of the anotherradio transceiver device. The method comprises transmitting, during thebeam training, a second set of occurrences of the reference signalaccording to the antenna array configuration information.

According to a sixth aspect there is presented a radio transceiverdevice for beam training of another radio transceiver device. The radiotransceiver device comprises processing circuitry. The processingcircuitry is configured to cause the radio transceiver device totransmit, during the beam training, a first set of occurrences of areference signal according to antenna array configuration information ofthe another radio transceiver device. The processing circuitry isconfigured to cause the radio transceiver device to transmit, during thebeam training, a second set of occurrences of the reference signalaccording to the antenna array configuration information.

According to a seventh aspect there is presented a radio transceiverdevice for beam training of another radio transceiver device. The radiotransceiver device comprises a transmit module configured to transmit,during the beam training, a first set of occurrences of a referencesignal according to antenna array configuration information of theanother radio transceiver device. The radio transceiver device comprisesa transmit module configured to transmit, during the beam training, asecond set of occurrences of the reference signal according to theantenna array configuration information.

According to an eight aspect there is presented a computer program forbeam training of another radio transceiver device, the computer programcomprising computer program code which, when run on processing circuitryof a radio transceiver device, causes the radio transceiver device toperform a method according to the fifth aspect.

According to a ninth aspect there is presented a computer programproduct comprising a computer program according to at least one of thefourth aspect and the eight aspect and a computer readable storagemedium on which the computer program is stored. The computer readablestorage medium could be a non-transitory computer readable storagemedium.

Advantageously these methods, these radio transceiver devices, and thesecomputer programs provide efficient beam training of the radiotransceiver device.

Advantageously the proposed beam training has less overhead compared toconventional beam training, without the performance being deteriorated.

Other objectives, features and advantages of the enclosed embodimentswill be apparent from the following detailed disclosure, from theattached dependent claims as well as from the drawings.

Generally, all terms used in the claims are to be interpreted accordingto their ordinary meaning in the technical field, unless explicitlydefined otherwise herein. All references to “a/an/the element,apparatus, component, means, module, step, etc.” are to be interpretedopenly as referring to at least one instance of the element, apparatus,component, means, module, step, etc., unless explicitly statedotherwise. The steps of any method disclosed herein do not have to beperformed in the exact order disclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive concept is now described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram illustrating a communications networkaccording to embodiments;

FIG. 2 is a schematic illustration of a radio transceiver deviceaccording to an embodiment;

FIGS. 3 and 4 are flowcharts of methods according to embodiments;

FIG. 5 is a schematic illustration of beam training performed by a radiotransceiver device according to an embodiment;

FIG. 6 is a schematic illustration of a scheduled sequence of OFDMsymbols during beam training according to an embodiment;

FIG. 7 is a schematic diagram showing functional units of a radiotransceiver device according to an embodiment;

FIG. 8 is a schematic diagram showing functional modules of a radiotransceiver device according to an embodiment;

FIG. 9 is a schematic diagram showing functional units of a radiotransceiver device according to an embodiment;

FIG. 10 is a schematic diagram showing functional modules of a radiotransceiver device according to an embodiment; and

FIG. 11 shows one example of a computer program product comprisingcomputer readable means according to an embodiment.

DETAILED DESCRIPTION

The inventive concept will now be described more fully hereinafter withreference to the accompanying drawings, in which certain embodiments ofthe inventive concept are shown. This inventive concept may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided by way of example so that this disclosure will be thorough andcomplete, and will fully convey the scope of the inventive concept tothose skilled in the art. Like numbers refer to like elements throughoutthe description. Any step or feature illustrated by dashed lines shouldbe regarded as optional.

FIG. 1 is a schematic diagram illustrating a communications network 100where embodiments presented herein can be applied. The communicationsnetwork 100 is typically a fifth (5G) telecommunications network andthus supports any thereto applicable 3GPP telecommunications standard.

The communications network 100 comprises a radio transceiver device 300that is configured to provide network access to radio transceiver device200 in a cell of a radio access network 110. The radio access network110 is operatively connected to a core network 120. The core network 120is in turn operatively connected to a service network 130, such as theInternet. Radio transceiver device 200 is thereby, via radio transceiverdevice 300, enabled to access services of, and exchange data with, theservice network 130.

Examples of network nodes 200 are radio access network nodes, radio basestations, base transceiver stations, Node Bs, evolved Node Bs, g NodeBs, access points, and access nodes. Examples of radio transceiverdevice 200 are wireless devices, mobile stations, mobile phones,handsets, wireless local loop phones, user equipment (UE), smartphones,laptop computers, tablet computers, network equipped sensors, networkequipped vehicles, and so-called Internet of Things devices.

In the illustrative example of FIG. 1, radio transceiver device 300provides network access in the cell by transmitting signals to, andreceiving signals from, radio transceiver device 200 in beams belongingto a set of beams 140. The signals could be transmitted from, andreceived by, a TRP 400 of radio transceiver device 300. The TRP 400could form an integral part of radio transceiver device 300 or bephysically separated from radio transceiver device 300. Further, radiotransceiver device 200 is configured to transmit signals to, and receivesignals from, radio transceiver device 300 in beams belonging to a setof beams 150.

FIG. 2 is a schematic illustration of part of radio transceiver device200 according to an embodiment. Particularly, according to theillustrative example of FIG. 2, radio transceiver device 200 has twoantenna arrays 240 a, 240 b that are connectable to one single basebandunit 250 via a switch 260. The antenna arrays 240 a, 240 b, and thebaseband unit 250 might be part of a communications interface 220 ofradio transceiver device 200. Although the illustrative example of FIG.2 shows a radio transceiver device 200 having two antenna arrays 240 a,240 b and one single baseband unit 250, the herein disclosed embodimentsare applicable to radio transceiver devices 200 having any number ofbaseband chains and antenna arrays.

The embodiments disclosed herein relate to mechanisms for beam trainingof radio transceiver device 200. In order to obtain such mechanismsthere is provided a radio transceiver device 200, a method performed byradio transceiver device 200, a computer program product comprisingcode, for example in the form of a computer program, that when run onprocessing circuitry of radio transceiver device 200, causes radiotransceiver device 200 to perform the method. In order to obtain suchmechanisms there is further provided a radio transceiver device 300, amethod performed by radio transceiver device 300, and a computer programproduct comprising code, for example in the form of a computer program,that when run on processing circuitry of radio transceiver device 300,causes radio transceiver device 300 to perform the method.

Reference is now made to FIG. 3 illustrating embodiments of methods forbeam training of radio transceiver device 200 as performed by radiotransceiver device 200 itself. As noted above, radio transceiver device200 comprises at least two antenna arrays 240 a, 240 b.

During the beam training radio transceiver device 200, starts with usingone wide beam per antenna array and then evaluates, according to somemetric, which antenna array is best. Hence, transceiver device 200 isconfigured to perform step S106:

S106: Radio transceiver device 200 receives, during the beam training, afirst set of occurrences of a reference signal using all the antennaarrays 240 a, 240 b and such that one respective occurrence of thereference signal is received in one single wide beam A0, B0 at each ofall the antenna arrays 240 a, 240 b.

Radio transceiver device 200 then switches to the best antenna array andevaluates narrow beams for that antenna array. Hence, transceiver device200 is configured to perform step S110:

S100: Radio transceiver device 200 receives, during the beam training, asecond set of occurrences of the reference signal using less than allantenna arrays 240 a, 240 b and such that one respective occurrence ofthe reference signal is received in each respective narrow beam B1, B2,. . . , B8 at each of the less than all antenna arrays 240 a, 240 b.

Which of the less than all antenna arrays 240 a, 240 b to receive thesecond set of occurrences of the reference signal is determined based onevaluation of reception of the first set of occurrences of the referencesignal at each of all the antenna arrays 240 a, 240 b.

Hence, during the beam training, radio transceiver device 200 firstevaluates which antenna arrays that is best, and then evaluates, for thebest antenna array, which beam is best for transceiver device 200.

Embodiments relating to further details of beam training of radiotransceiver device 200 as performed by radio transceiver device 200 willnow be disclosed.

There could be different ways for radio transceiver device 200 toreceive the second set of occurrences of the reference signal.

In some aspects, only one single antenna array is used for receiving thesecond set of occurrences of the reference signal. Particularly,according to an embodiment, only a single one of the antenna arrays 240a, 240 b is used when receiving the second set of occurrences of thereference signal.

In some aspects, only one single antenna array is eliminated after thefirst set of occurrences of the reference signal has been received.Particularly, according to an embodiment, the less than all antennaarrays 240 a, 240 b includes all but one of all the antenna arrays 240a, 240 b.

In some aspects, at least one antenna array is eliminated after thefirst set of occurrences of the reference signal has been received andat least two antenna arrays are used for receiving the second set ofoccurrences of the reference signal. Particularly, according to anembodiment, radio transceiver device 200 comprises at least threeantenna arrays 240 a, 240 b, and the less than all antenna arrays 240 a,240 b includes at least two antenna arrays 240 a, 240 b.

In some aspects the reception of the second set of occurrences of thereference signal enables radio transceiver device 200 to select one beamfor further reception of signals. Particularly, according to anembodiment, radio transceiver device 200 is configured to perform(optional) step S112:

S112: Radio transceiver device 200 selects one of the narrow beams B1,B2, . . . , B8 to use for further reception of signals based onevaluation of reception of the second set of occurrences of thereference signal at the less than all antenna arrays 240 a, 240 b.

In some aspects channel reciprocity is assumed and the same selectednarrow beam might thus be used for both reception and transmission ofsignals. Particularly, according to an embodiment, the selected one ofthe narrow beams B1, B2, . . . , B8 also is selected for transmission ofsignals.

In some aspects radio transceiver device 200 signals its antenna arrayconfiguration to the sender of the reference signal in order for thesender to correctly schedule at least the transmission of the first setof occurrences of the reference signal and the second set of occurrencesof the reference signal. Particularly, according to an embodiment, thereference signal is transmitted from radio transceiver device 300 andradio transceiver device 200 is configured to perform (optional) stepS102:

S102: Radio transceiver device 200 signals antenna array configurationinformation to radio transceiver device 300. The antenna arrayconfiguration information specifies how many antenna arrays 240 a, 240 bradio transceiver device 200 comprises and how many narrow beams B1, B2,. . . , B8 per antenna array 240 a, 240 b radio transceiver device 200is to evaluate during the beam training.

There might be different metrics used by radio transceiver device 200 toevaluate the reception of the first set of occurrences of the referencesignal. Particularly, according to an embodiment, the evaluation ofreception of the first set of occurrences of the reference signal isbased on measurements of at least one of reference signal received power(RSRP) and signal to interference plus noise ratio (SINR) of the firstset of occurrences of the reference signal in the single wide beam ateach respective one of all the antenna arrays 240 a, 240 b.

In some aspects there is a time gap between the first set of occurrencesof the reference signal and the second set of occurrences of thereference signal. Particularly, according to an embodiment, the secondset of occurrences of the reference signal is received after a timeinterval after receiving the first set of occurrences of the referencesignal.

In order to minimize the overhead signaling, during the time it takesfor radio transceiver device 200 to evaluate which antenna array 240 a,240 b that was best, radio transceiver device 300 could schedule radiotransceiver device 200 with other useful transmissions, for example dataon a physical downlink control channel (PDCCH) or physical downlinkshared channel PDSCH. That is, in some aspects the time gap is used fortransmission of data to radio transceiver device 200. Particularly,according to an embodiment, radio transceiver device 200 is configuredto perform (optional) step S108:

S108: Radio transceiver device 200 receives control and/or data duringthe time interval.

Radio transceiver device 200 might receive the data in step S108 using amost-recently used narrow beam for receiving data.

In some aspects the length of the time gap is adapted to processingspeed of radio transceiver device 200. Particularly, according to anembodiment, the time interval has a length based on processing speed ofthe radio transceiver device 200 to evaluate the reception of the firstset of occurrences of the reference signal.

In some aspects radio transceiver device 200 signals its processingconfiguration to the sender of the reference signal in order for thesender to correctly adapting the length used for the transmission ofdata during the time interval. Particularly, according to an embodiment,the reference signal is transmitted from radio transceiver device 300,and radio transceiver device 200 is configured to perform (optional)step S104:

S104: Radio transceiver device 200 signals processing configurationinformation to radio transceiver device 300. The processingconfiguration information specifies the processing speed.

In some aspects the length of the time gap is adapted to the periodicitythat certain signals, such as a synchronization signal (SS) physicalbroadcast channel (PBCH) block, or just synchronization signal block(SSB) for short, are transmitted with. For example, each SSB mightconsist of four OFDM symbols; one representing a primary synchronizationsignal (PSS), two representing PBCH signals, and one representing asecondary synchronization signal (SSS). The SSB is might be transmittedwith a periodicity of about 5 to 100 ms.

It is thereby possible for radio transceiver device 200 to performmeasurements on at most four antenna arrays (such as for beams A0 andB0) for one SSB and during the next SSB perform measurements on at mostfour beams (such as for beams B1-B4) for one antenna array and thenduring the next SSB again perform measurements on at most four beams(such as for beams B5-B8) for the same antenna array, and so on.

There could be different kinds of restrictions on radio transceiverdevice 200 with regards to its transmission and reception capabilities.In some aspects radio transceiver device 200 is restricted to onlyreceive in one beam at the time. Particularly, according to anembodiment, radio transceiver device 200 only is capable of using onesingle antenna array 240 a, 240 b at a time for reception of thereference signal.

There could be different kinds of configurations of radio transceiverdevice 200 with regards to the antenna arrays 240 a, 240 b. For example,as in the illustrative example of FIG. 2, all antenna arrays might beoperatively connected to the same baseband unit 250. Particularly,according to an embodiment, all the antenna arrays 240 a, 240 b areoperatively connectable to one common baseband unit 250 in radiotransceiver device 200. The switch 260 might then be used to selectivelyconnect the different antenna arrays 240 a, 240 b to the baseband unit250 at different times.

There could be different ways for radio transceiver device 200 togenerate the wide beams A0, B0 and the narrow beams B1-B8. Particularly,according to an embodiment, radio transceiver device 200 is arranged foranalog beamforming.

In further detail, by applying principles disclosed in documentWO2011/050866A1 it is, for example, possible to generate as wide arraybeam widths (for the beams A0, B0) as the element beam width of theantenna arrays 240 a, 240 b, regardless of how many antenna elementsthere are in the antenna array 240 a, 240 b, thus resulting indual-polarization beamforming. Dual-polarization beamforming can thus beused to selectively widening or narrowing the beams as needed. Hence,principles disclosed in document WO2011/050866A1 can be applied to theanalog beamforming network in order to generate the wide beams A0, B0 aswell as the narrow beams B1-B8. Other examples of principles that couldbe used to generate wide beams A0, B0 as needed are based on optimizingcomplex weights of the antenna array 240 a, 240 b of the analogbeamforming network or by muting some antenna elements of the antennaarray 240 a, 240 b. A way to generate wide receive beams 140 a, 140 bwith phase shifts only is by means of the array expansion techniquedescribed in WO2016141961 A1. WO2016141961 A1 relates to beam formingusing an antenna array comprising dual polarized elements. By adaptingand then applying the expansion technique described in WO2016141961 A1it is possible to generate as wide beams or as narrow beams as possibleusing phase shifts only at the antenna arrays 240 a, 240 b.

Reference is now made to FIG. 4 illustrating embodiments of methods forbeam training of radio transceiver device 200 as performed by radiotransceiver device 300.

As disclosed above, radio transceiver device 200 is assumed to receive afirst set of occurrences of a reference signal from a sender, such asfrom radio transceiver device 300. Radio transceiver device 300 istherefore configured to perform step S206:

S206: Radio transceiver device 300 transmits, during the beam training,a first set of occurrences of a reference signal according to antennaarray configuration information of radio transceiver device 200.

As disclosed above, radio transceiver device 200 is assumed to receive asecond set of occurrences of a reference signal from a sender, such asfrom radio transceiver device 200. Radio transceiver device 300 istherefore configured to perform step S210:

S210: Radio transceiver device 300 transmits, during the beam training,a second set of occurrences of the reference signal according to theantenna array configuration information.

Embodiments relating to further details of beam training of anotherradio transceiver device 200 as performed by radio transceiver device300 will now be disclosed.

As disclosed above, in some aspects radio transceiver device 200 has anantenna array configuration. Particularly, according to an embodiment,the antenna array configuration information specifies how many antennaarrays 240 a, 240 b radio transceiver device 200 comprises and how manynarrow beams B1, B2, . . . , B8 per antenna array 240 a, 240 b radiotransceiver device 200 is to evaluate during the beam training.

Radio transceiver device 300 might then adapt the first set ofoccurrences of the reference signal and the second set of occurrences ofthe reference signal according to the antenna array configurationinformation. Particularly, according to an embodiment, the first set ofoccurrences includes as many occurrences as needed for one occurrence ofthe reference signal to be received using each of the antenna arrays 240a, 240 b and the second set of occurrences includes as many occurrencesas there are narrow beams.

As disclosed above, in some aspects radio transceiver device 200 signalsits antenna array configuration to radio transceiver device 300.Particularly, according to an embodiment, radio transceiver device 300is configured to perform (optional) step S202:

S202: Radio transceiver device 300 receives the antenna arrayconfiguration information from radio transceiver device 200 prior totransmitting the first set of occurrences of the reference signals.

As disclosed above, in some aspects there is a time gap between thefirst set of occurrences of the reference signal and the second set ofoccurrences of the reference signal. Particularly, according to anembodiment, the second set of occurrences of the reference signal istransmitted after a time interval after transmitting the first set ofoccurrences of the reference signal.

As disclosed above, in some aspects the time gap is used fortransmission of data to radio transceiver device 200. Particularly,according to an embodiment, radio transceiver device 200 is configuredto perform (optional) step S208:

S208: Radio transceiver device 300 transmits control and/or data toradio transceiver device 200 during the time interval.

This means that, when each occurrences of the reference signal istransmitted using one OFDM symbol, radio transceiver device 300 willfirst transmit the reference signal with one occurrence of the first setof occurrences of the reference signal in one respective OFDM symbol,then schedule other data on one or more OFDM symbols, and then transmitthe reference signal with one occurrence of the second set ofoccurrences of the reference signal in one respective OFDM symbol.

As disclosed above, in some aspects the length of the time gap isadapted to processing speed of radio transceiver device 200.Particularly, according to an embodiment, the time interval has a lengthbased on processing speed of radio transceiver device 200 to evaluatereception of the first set of occurrences of the reference signal.

As disclosed above, in some aspects radio transceiver device 200 signalsits processing configuration to radio transceiver device 300.Particularly, according to an embodiment, radio transceiver device 300is configured to perform (optional) step S204:

S204: Radio transceiver device 300 receives processing configurationinformation from radio transceiver device 200. The processingconfiguration information specifies the processing speed.

Radio transceiver device 300 might then, for example select how manyOFDM symbols with data to transmit during the time interval between thefirst set of occurrences of the reference signal and the second set ofoccurrences of the reference signal.

As disclosed above, in some aspects the length of the time gap isadapted to the periodicity that certain signals, such as SSB, aretransmitted with.

There might be different ways to facilitate transmission of thereference signals in each of the occurrences. Particularly, according toan embodiment, the reference signal in each of the occurrences occupiesone OFDM symbol.

There might be different examples of reference signals. Particularly,according to an embodiment, the reference signal is either a CSI-RS, anSSB, or a sounding reference signal (SRS). The reference signals aretypically CSI-RS or SSB when radio transceiver device 200 is a terminaldevice and radio transceiver device 300 is a network node. The referencesignals are typically SRS when radio transceiver device 200 is a networknode and radio transceiver device 300 is a terminal device.

One particular embodiment for beam training of radio transceiver device200 based on at least some of the above disclosed embodiments will nowbe disclosed in detail.

FIG. 5 illustrates one embodiment of radio transceiver device 200 asapplied during a UE RX beam training procedure. In this illustrativeembodiment radio transceiver device 200 is thus typically a terminaldevice and radio transceiver device 300 is typically a network node.

It is assumed that radio transceiver device 300 sequentially transmits11 OFDM symbols. Further, in this illustrative example, radiotransceiver device 300 has scheduled transmission of CSI-RS in the firsttwo OFDM symbols, data in the third OFDM symbol, and CSI-RS in OFDMsymbols 4-11.

OFDM symbol 1: During transmission of the first OFDM symbol, radiotransceiver device 200 has the baseband chain 250 connected to the leftantenna array 240 a through the switch 260 and creates a wide beam B0for that antenna array.

OFDM symbol 2: During transmission of the second OFDM symbol, radiotransceiver device 200 has the baseband chain 250 connected to the rightantenna array 240 b and applies a wide beam B0 for that antenna array.

The wide beams A0, B0 could for example be generated by using phasetapering and/or amplitude tapering. Further examples to generate beamsbeing as wide as needed (and as narrow as needed) have been disclosedabove.

OFDM symbol 3: During transmission of the third OFDM symbol, radiotransceiver device 200 evaluates which antenna array has the strongestRSRP, which will take some time (one or multiple OFDM symbols dependingon processing capacity at radio transceiver device 200). During thistime, radio transceiver device 200 might be scheduled with othertransmissions (e.g. control data transmitted on PDCCH or PDSCH) that canbe received by radio transceiver device 200 whilst performing RSRPcalculations. Radio transceiver device 200 might during the third OFDMsymbol temporarily switch to the previously known best UE RX beam toproperly receive the so-called other transmissions.

OFDM symbols 4-11: When radio transceiver device 200 has evaluated whichantenna array that has the highest RSRP, radio transceiver device 200connects the baseband to that antenna array and starts sweeping throughthe narrow beams for that antenna array. In the present illustrativeexample it is assumed that the right antenna array has highest RSRP andthus that narrow beams B1-B8 are swept through.

In the example of FIG. 5, a total of to OFDM symbols are scheduled withCSI-RS for finding a suitable UE RX beam, which is 6 OFDM symbols lesscompared to if 8 narrow beams are swept through sequentially for eachantenna array (i.e., 16 narrow beams in total).

FIG. 6 illustrates the scheduling of OFDM symbols for the example ofFIG. 5. Slots are not explicitly marked in FIG. 6. All 11 OFDM symbolscontain CSI-RS except the third OFDM symbol which contains control ordata, such as transmitted on PDCCH or PDSCH. During this third OFDMsymbol radio transceiver device 200 determines which panel that hashighest RSRP.

FIG. 7 schematically illustrates, in terms of a number of functionalunits, the components of radio transceiver device 200 according to anembodiment. Processing circuitry 210 is provided using any combinationof one or more of a suitable central processing unit (CPU),multiprocessor, microcontroller, digital signal processor (DSP), etc.,capable of executing software instructions stored in a computer programproduct 1100 a (as in FIG. 11), e.g. in the form of a storage medium230. The processing circuitry 210 may further be provided as at leastone application specific integrated circuit (ASIC), or fieldprogrammable gate array (FPGA).

Particularly, the processing circuitry 210 is configured to cause radiotransceiver device 200 to perform a set of operations, or steps,S102-S112, as disclosed above. For example, the storage medium 230 maystore the set of operations, and the processing circuitry 210 may beconfigured to retrieve the set of operations from the storage medium 230to cause radio transceiver device 200 to perform the set of operations.The set of operations may be provided as a set of executableinstructions. Thus the processing circuitry 210 is thereby arranged toexecute methods as herein disclosed.

The storage medium 230 may also comprise persistent storage, which, forexample, can be any single one or combination of magnetic memory,optical memory, solid state memory or even remotely mounted memory.

Radio transceiver device 200 may further comprise a communicationsinterface 220 for communications with other entities, nodes, functions,and devices of the communications network 100, such as radio transceiverdevice 300. As such the communications interface 220 may comprise one ormore transmitters and receivers, comprising analogue and digitalcomponents.

Signals could be transmitted from, and received by, at least two antennaarrays 240 a, 240 b of radio transceiver device 200. The at least twoantenna arrays 240 a, 240 b could form an integral part of radiotransceiver device 200 or be physically separated from radio transceiverdevice 300. The communications interface 220 might thus optionallycomprise the at least two antenna arrays 240 a, 240 b, as in FIG. 2.

The processing circuitry 210 controls the general operation of radiotransceiver device 200 e.g. by sending data and control signals to thecommunications interface 220 and the storage medium 230, by receivingdata and reports from the communications interface 220, and byretrieving data and instructions from the storage medium 230. Othercomponents, as well as the related functionality, of radio transceiverdevice 200 are omitted in order not to obscure the concepts presentedherein.

FIG. 8 schematically illustrates, in terms of a number of functionalmodules, the components of radio transceiver device 200 according to anembodiment. Radio transceiver device 200 of FIG. 8 comprises a number offunctional modules; a receive module 2100 c configured to perform stepS106 and a receive module 210 e configured to perform step S110. Radiotransceiver device 200 of FIG. 8 may further comprise a number ofoptional functional modules, such as any of a signal module 210 aconfigured to perform step S102, a signal module 210 b configured toperform step S104, a receive module 210 d configured to perform stepS108, and a select module 210 f configured to perform step S112. Ingeneral terms, each functional module 210 a-210 f may be implemented inhardware or in software. Preferably, one or more or all functionalmodules 210 a-210 f may be implemented by the processing circuitry 210,possibly in cooperation with the communications interface 220 and/or thestorage medium 230. The processing circuitry 210 may thus be arranged tofrom the storage medium 230 fetch instructions as provided by afunctional module 210 a-210 f and to execute these instructions, therebyperforming any steps of radio transceiver device 200 as disclosedherein.

FIG. 9 schematically illustrates, in terms of a number of functionalunits, the components of radio transceiver device 300 according to anembodiment. Processing circuitry 310 is provided using any combinationof one or more of a suitable central processing unit (CPU),multiprocessor, microcontroller, digital signal processor (DSP), etc.,capable of executing software instructions stored in a computer programproduct 1110 b (as in FIG. 11), e.g. in the form of a storage medium330. The processing circuitry 310 may further be provided as at leastone application specific integrated circuit (ASIC), or fieldprogrammable gate array (FPGA).

Particularly, the processing circuitry 310 is configured to cause radiotransceiver device 300 to perform a set of operations, or steps,S202-S210, as disclosed above. For example, the storage medium 330 maystore the set of operations, and the processing circuitry 310 may beconfigured to retrieve the set of operations from the storage medium 330to cause radio transceiver device 300 to perform the set of operations.The set of operations may be provided as a set of executableinstructions. Thus the processing circuitry 310 is thereby arranged toexecute methods as herein disclosed.

The storage medium 330 may also comprise persistent storage, which, forexample, can be any single one or combination of magnetic memory,optical memory, solid state memory or even remotely mounted memory.

Radio transceiver device 300 may further comprise a communicationsinterface 320 for communications with other entities, nodes, functions,and devices of the communications network 100, such as radio transceiverdevice 200. As such the communications interface 320 may comprise one ormore transmitters and receivers, comprising analogue and digitalcomponents.

Signals could be transmitted from, and received by, a TRP 400 of radiotransceiver device 300. The TRP 400 could form an integral part of radiotransceiver device 300 or be physically separated from radio transceiverdevice 300. The communications interface 220 might thus optionallycomprise the TRP 400.

The processing circuitry 310 controls the general operation of radiotransceiver device 300 e.g. by sending data and control signals to thecommunications interface 320 and the storage medium 330, by receivingdata and reports from the communications interface 320, and byretrieving data and instructions from the storage medium 330. Othercomponents, as well as the related functionality, of radio transceiverdevice 300 are omitted in order not to obscure the concepts presentedherein.

FIG. 10 schematically illustrates, in terms of a number of functionalmodules, the components of radio transceiver device 300 according to anembodiment. Radio transceiver device 300 of FIG. 10 comprises a numberof functional modules; a transmit module 310 c configured to performstep S206 and a transmit module 310 e configured to perform step S210.Radio transceiver device 300 of FIG. 10 may further comprise a number ofoptional functional modules, such as any of a receive module 310 aconfigured to perform step S202, a receive module 310 b configured toperform step S204, and a transmit module 310 d configured to performstep S208. In general terms, each functional module 310 a-310 e may beimplemented in hardware or in software. Preferably, one or more or allfunctional modules 310 a-310 e may be implemented by the processingcircuitry 310, possibly in cooperation with the communications interface320 and/or the storage medium 330. The processing circuitry 310 may thusbe arranged to from the storage medium 330 fetch instructions asprovided by a functional module 310 a-310 e and to execute theseinstructions, thereby performing any steps of radio transceiver device300 as disclosed herein.

Radio transceiver radio transceiver device 300 may be provided as astandalone device or as a part of at least one further device. Forexample, radio transceiver device 300 may be provided in a node of theradio access network or in a node of the core network. Alternatively,functionality of radio transceiver device 300 may be distributed betweenat least two devices, or nodes. These at least two nodes, or devices,may either be part of the same o10 network part (such as the radioaccess network or the core network) or may be spread between at leasttwo such network parts. In general terms, instructions that are requiredto be performed in real time may be performed in a device, or node,operatively closer to the cell than instructions that are not requiredto be performed in real time.

Thus, a first portion of the instructions performed by radio transceiverdevice 300 may be executed in a first device, and a second portion ofthe of the instructions performed by radio transceiver device 300 may beexecuted in a second device; the herein disclosed embodiments are notlimited to any particular number of devices on which the instructionsperformed by radio transceiver device 300 may be executed. Hence, themethods according to the herein disclosed embodiments are suitable to beperformed by radio transceiver device 300 residing in a cloudcomputational environment. Therefore, although a single processingcircuitry 310 is illustrated in FIG. 9 the processing circuitry 310 maybe distributed among a plurality of devices, or nodes. The same appliesto the functional modules 310 a-310 e of FIG. 10 and the computerprogram 1120 b of FIG. 11 (see below).

FIG. 11 shows one example of a computer program product 1110 a, 1110 bcomprising computer readable means 1130. On this computer readable means1130, a computer program 1120 a can be stored, which computer program1120 a can cause the processing circuitry 210 and thereto operativelycoupled entities and devices, such as the communications interface 220and the storage medium 230, to execute methods according to embodimentsdescribed herein. The computer program 1120 a and/or computer programproduct 1110 a may thus provide means for performing any steps of radiotransceiver device 200 as herein disclosed. On this computer readablemeans 1130, a computer program 1120 b can be stored, which computerprogram 1120 b can cause the processing circuitry 310 and theretooperatively coupled entities and devices, such as the communicationsinterface 320 and the storage medium 330, to execute methods accordingto embodiments described herein. The computer program 1120 b and/orcomputer program product 1110 b may thus provide means for performingany steps of radio transceiver device 300 as herein disclosed.

In the example of FIG. 11, the computer program product 1110 a, 1110 bis illustrated as an optical disc, such as a CD (compact disc) or a DVD(digital versatile disc) or a Blu-Ray disc. The computer program product1110 a, 1110 b could also be embodied as a memory, such as a randomaccess memory (RAM), a read-only memory (ROM), an erasable programmableread-only memory (EPROM), or an electrically erasable programmableread-only memory (EEPROM) and more particularly as a non-volatilestorage medium of a device in an external memory such as a USB(Universal Serial Bus) memory or a Flash memory, such as a compact Flashmemory. Thus, while the computer program 1120 a, 1120 b is hereschematically shown as a track on the depicted optical disk, thecomputer program 1120 a, 1120 b can be stored in any way which issuitable for the computer program product 1110 a, 1110 b.

The inventive concept has mainly been described above with reference toa few embodiments. However, as is readily appreciated by a personskilled in the art, other embodiments than the ones disclosed above areequally possible within the scope of the inventive concept, as definedby the appended patent claims.

The invention claimed is:
 1. A method for beam training of another radiotransceiver device, the method being performed by a radio transceiverdevice, the method comprising: transmitting, during the beam training, afirst set of occurrences of a reference signal according to antennaarray configuration information of the another radio transceiver device,wherein the first set of occurrences includes as many occurrences asneeded for one occurrence of the reference signal to be received usingeach of the antenna arrays and the antenna array configurationinformation specifies how many antenna arrays the another radiotransceiver device comprises and how many narrow beams per antenna arraythe another radio transceiver device is to evaluate during the beamtraining; and transmitting, during the beam training, a second set ofoccurrences of the reference signal according to the antenna arrayconfiguration information after the first set of occurrences have beentransmitted, wherein the second set of occurrences includes as manyoccurrences as there are narrow beams.
 2. The method according to claim1, further comprising: receiving the antenna array configurationinformation from the another radio transceiver device prior totransmitting the first set of occurrences of the reference signals. 3.The method according to claim 1, wherein the second set of occurrencesof the reference signal is transmitted after a time interval aftertransmitting the first set of occurrences of the reference signal. 4.The method according to claim 3, further comprising: transmittingcontrol or data to the another radio transceiver device during the timeinterval.
 5. The method according to claim 4, wherein the time intervalhas a length based on processing speed of the another radio transceiverdevice to evaluate reception of the first set of occurrences of thereference signal.
 6. The method according to claim 5, furthercomprising: receiving processing configuration information from theanother radio transceiver device, the processing configurationinformation specifying the processing speed.
 7. A radio transceiverdevice for beam training of another radio transceiver device, the radiotransceiver device comprising processing circuitry, the processingcircuitry being configured to cause the radio transceiver device to:transmit, during the beam training, a first set of occurrences of areference signal according to antenna array configuration information ofthe another radio transceiver device, wherein the first set ofoccurrences includes as many occurrences as needed for one occurrence ofthe reference signal to be received using each of the antenna arrays andthe antenna array configuration information specifies how many antennaarrays the another radio transceiver device comprises and how manynarrow beams per antenna array the another radio transceiver device isto evaluate during the beam training; and transmit, during the beamtraining, a second set of occurrences of the reference signal accordingto the antenna array configuration information after the first set ofoccurrences have been transmitted, wherein the second set of occurrencesincludes as many occurrences as there are narrow beams.
 8. The radiotransceiver device according to claim 7, the processing circuitry beingconfigured to further cause the radio transceiver device to: receive theantenna array configuration information from the another radiotransceiver device prior to transmitting the first set of occurrences ofthe reference signals.
 9. The radio transceiver device according toclaim 7, wherein the second set of occurrences of the reference signalis transmitted after a time interval after transmitting the first set ofoccurrences of the reference signal.
 10. The radio transceiver deviceaccording to claim 9, the processing circuitry being configured tofurther cause the radio transceiver device to: transmit control or datato the another radio transceiver device during the time interval. 11.The radio transceiver device according to claim 10, wherein the timeinterval has a length based on processing speed of the another radiotransceiver device to evaluate reception of the first set of occurrencesof the reference signal.
 12. The radio transceiver device according toclaim 11, the processing circuitry being configured to further cause theradio transceiver device to: receive processing configurationinformation from the another radio transceiver device, the processingconfiguration information specifying the processing speed.
 13. Acomputer program product for beam training of another radio transceiverdevice, the computer program product comprising a non-transitorycomputer readable medium storing computer code which, when run onprocessing circuitry of a radio transceiver device, causes the radiotransceiver device to: transmit, during the beam training, a first setof occurrences of a reference signal according to antenna arrayconfiguration information of the another radio transceiver device,wherein the first set of occurrences includes as many occurrences asneeded for one occurrence of the reference signal to be received usingeach of the antenna arrays and the antenna array configurationinformation specifies how many antenna arrays the another radiotransceiver device comprises and how many narrow beams per antenna arraythe another radio transceiver device is to evaluate during the beam; andtransmit, during the beam training, a second set of occurrences of thereference signal according to the antenna array configurationinformation after the first set of occurrences have been transmitted,wherein the second set of occurrences includes as many occurrences asthere are narrow beams.